The high volume manufacture of some products requires the sorting and classifying of their component parts. For example, many products require the precise positioning and assembly of a variety of accurately manufactured parts to include extremely small and lightweight components. In general, such component parts must be formed with critical dimensions for a proper assembly. During manufacture these critical dimensions must be precisely measured and the parts sorted in lots corresponding to the specified dimensions. Sorting may be based on specific dimensioning of the parts or on the basis of good or reject parts.
As an example, parts may be formed in multi-cavity tooling where the critical dimensions may vary depending on the mold cavity. Products with very tight critical tolerances may often have many rejects due to tolerance match-ups of component parts that result in total tolerance variance outside of acceptable levels. A worst possible case is where a product is assembled with a tolerance variance right on the maximum allowable level. In this case, a product can pass final test and then fail in the field shortly after being placed into service.
Sorting machines for inspecting and separating specific component parts are well known in the prior art. Such sorting machines may use mechanical devices for measuring the parts such as the caliper device shown in U.S. Pat. No, 3,743,093 to Klancnik. In general such mechanical measuring devices are relatively slow and are limited with respect to the precision with which parts can be measured. They are typically limited to a few specially configured parts and are not easily reconfigured to adapt to other types of parts. U.S. Pat. Nos. 4,576,286 and 4,690,284 to Buckley et al disclose parts sorting systems in which wave energy of a single frequency is directed at the part. This wave energy is then analyzed to determine the dimensions and characteristics of the part. These prior art sorting systems also have certain short comings. Such sorting systems, for example, are relatively complicated and expensive and are also limited with respect to the precision of the measurements.
In addition to these limitations most prior systems are not designed to accomplish the inspection and sorting of a variety of accurately manufactured parts to include extremely small and light weight components. These operations require precision in both the movement of the component part into position for measurement, and in the force with which the component parts are handled and measured. Furthermore, for quality control purposes it is advantageous to verify that a part has been successfully moved through a particular station, inspected at the station, and the dimensional data transferred to a computer.
Another limitation of prior art sorting systems in general, is that separate stations are required for different functions of the system. As an example separate stations may be required for measuring a part, followed by stations for good part unload, bad part unload, and empty nest check. The requirement of multiple stations complicates such a sorting system, increases costs and limits the speed of the system
In view of these limitations of the prior art, it is an object of the present invention to provide an inspecting/sorting system in which a variety of manufactured parts, to include small and lightweight component parts can be handled and measured with extreme precision. It is a further object of the present invention to provide a sorting system in which parts can be measured with extreme precision at high speeds and at a single station. Yet another object of the present invention is to provide a sorting system in which replaceable measuring devices can be used to measure different features of parts such as the inside diameter, outside diameter, height, location, and run out of the part. Another object of the present invention is to provide a sorting system in which correct transport of a part through a measurement station